BACKGROUND: Norovirus is a highly contagious virus. It is also called “food poisoning” or “stomach flu,” but is not related to the flu (influenza). The virus can be caught from an infected person, contaminated water or food, or by touching contaminated surfaces. However, there is some evidence for spreading airborne(probably when viruses become airborne from projective vomiting and then land on). It is the most common cause of foodborne-diseases in the United States. Anyone can become infected with norovirus and can have it many times in their life. It can become dangerous for young children and older adults. The virus causes the stomach, intestines, or both to become inflamed, also known as acute gastroenteritis. Norovirus is the most common cause of acute gastroenteritis. It is responsible for 21 million illnesses, contributes to 70 thousand hospitalizations, and 800 deaths. (Source: www.cdc.gov).
SYMPTOMS: Norovirus causes diarrhea, nausea, stomach pain, throwing up, fever, headache, and body aches. The virus often causes patients to throw up or have diarrhea many times a day, putting them at risk for dehydration. Symptoms of dehydration include: dry mouth and throat, decrease in urination, and feeling dizzy when standing. Children who are dehydrated may cry without producing tears and can be unusually sleep or fussy. To prevent dehydration, patients should drink plenty of liquids to replace fluids that have been lost. Sports drinks can help with mild dehydration, but they cannot replace important nutrients and minerals. Oral rehydration fluids are available over the counter and are found to be most helpful for mild dehydration. (Source: www.cdc.gov).
NEW TECHNOLOGY: There is no specific medicine to treat people with the norovirus. The norovirus infection cannot be treated with antibiotics because it is a viral infection, not a bacterial infection. Last year, a nasal spray vaccine was tested on 90 volunteers. One third of those who got the vaccine developed symptoms related to the norovirus. Researchers believe the nasal vaccine only worked against one of the genetic strains of norovirus instead of multiple strains. The new injectable vaccine works against two, resulting in a cross-reaction that provides added protection. In the new study, participants received two injections in their arm of vaccine or placebo four weeks apart. There were no serious side effects related to the use of the vaccine. Researchers used blood tests to check for evidence of virus-fighting antibodies. Compared to placebo, participants of all ages mounted a rapid antibody response. Researchers believe that the new vaccine will result in patients having fewer symptoms than those getting a placebo. (Source: www.webmd.com)
John Treanor, MD, Professor of Medicine, Microbiology, and Immunology, and Chief of Infectious Diseases Division at the University of Rochester Medical Center, talks about a possible vaccine for Norovirus.
What is Norovirus?
Dr. Treanor: Noroviruses are probably the most common infectious cause of acute gastroenteritis in the United States. They are very common and they cause a typical illness characterized mostly by vomiting. When you have Norovirus, you know it. You will have very intense vomiting for about 24 hours and sometimes it is accompanied by diarrhea. However, not always and its associated with some fever and some muscle aches. Most people will recovery completely over the next day or two.
How common is it?
Dr. Treanor: It is clearly the most common cause of gastroenteritis. Most people will have an episode or two every year. It seems like perhaps it is more common in people who are living in close circumstances with lots of other people, but everybody is going to get Norovirus or one of the related viruses at some point through their life.
Is it an umbrella term for lots of viruses?
Dr. Treanor: One of the things about this virus is it is very infectious. When you have it, although you recover quickly, you continue to shed it from your body for many days afterwards. It only takes the tiniest dose to infect the next person. So the characteristic of Norovirus is lots of other people get sick; what they call the secondary attack rate is very high because it is so contagious.
Is that why cruise ships have such a problem with it?
Dr. Treanor: Absolutely; any situation where you have people living in close proximity to each other. When a Norovirus outbreak gets started, it is very tough to stop.
How serious is it or how serious can it get?
Dr. Treanor: For most people it is going to be a very self-limited illness, but we have recognized that in older adults, there can even be deaths associated with Norovirus. The CDC estimates, it’s not a large number, but something like 700 deaths associated with Norovirus every year, mostly in older people or people with compromised immune systems.
Does it affect infants and toddlers the same? Is it like the flu where it is worse for infants and older people or is Norovirus not as dangerous for infants?
Dr. Treanor: It is really not dangerous for toddlers and infants. However, it does generate a lot of illness and emergency room visits for gastroenteritis, but it usually is resolved by itself eventually.
Since for most people it resolves itself by itself fairly quickly, what is the need for a vaccine? Why were you studying that?
Dr. Treanor: It is a very common illness. When you have it, you are very disabled. It is really tough to get up and go to work or do anything else while you are having Norovirus because you are throwing up every hour. So, although a vaccine would not be designed to prevent deaths due to Norovirus, you could prevent a tremendous amount of disability in this country with a vaccine that was effective. For example, the Department of Defense is very interested in trying to find vaccines or other ways to prevent Norovirus because there have been some major outbreaks of Norovirus in military camps and bases which actually compromises readiness and so this is an important problem for them to control.
Are there lots of different Noroviruses where a vaccine might be similar to a flu, where you might get one every year? Is that the idea?
Dr. Treanor: There are some amazing parallels between the Noroviruses and the flu. One of them is that there does appear to be a form of antigenic change over time with the Noroviruses where the predominant strain is eventually replaced by another strain. So, it is possible that if we were using an effective Norovirus vaccine we might have to update it from time to time.
What has your research shown? What have you studied?
Dr. Treanor: I am involved in a project that involves a lot of investigators in many centers and it is all designed to try and evaluate one particular candidate “virus-like particle” vaccine for Norovirus; which means that the protein is there, but the RNA isn’t and so it does not replicate or cause disease. It has been given to people via muscle and also nasally. It can stimulate antibody which in theory should be protective against Norovirus.